<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        .parent{

            display: flex;
            justify-content: space-between;

            align-items: center;
            width:550px;
            height:380px;
            background-color: darkblue;
        }
        .item{
            /*开启flex后float无用，定位可以（子绝父相）*/
            float:left;

            width:100px;
            height:100px;
            background-color: darkgoldenrod;
        }
        .parent .item:nth-child(2){
            align-self:flex-end;
            align-self: flex-start;
        }


    </style>
</head>
<body>
<div class="parent">
    <div class="item">1</div>
    <div class="item" style="background-color: saddlebrown">2</div>
    <div class="item">3</div>

</div>
</body>
</html>